During the one-year research period, the study will focus on the impact of the solar radiation spectrum on the performance of photovoltaic (PV) modules, considering different PV technologies. Special attention will be given to the analysis of existing models used for synthesizing the solar spectrum under clear-sky conditions, as well as to the evaluation of advanced models capable of accurately representing spectral characteristics under cloudy or variable atmospheric conditions. The variability of the solar spectrum across different European regions will be examined, with particular emphasis on climate-dependent correction factors used to express these spectral variations.

In parallel with theoretical analysis and modelling, experimental testing of PV module and system performance under real operating conditions will be continued. This part of the research will focus on investigating the influence of surface soiling (e.g., dust, pollen, industrial particulates) and partial shading on the electrical characteristics of individual PV modules and entire PV arrays. The tests will be conducted on modules based on both crystalline and amorphous silicon technologies, enabling a direct comparison of their behavior under identical environmental conditions.

The experimental results will serve as a basis for the development of a mathematical model that quantifies the impact of soiling on the electrical performance of PV modules. The model will be developed and implemented using the MATLAB/Simulink software environment, and its accuracy will be validated against real-world measurement data. Based on the research findings, recommendations will be formulated for the design and maintenance of PV systems in different climate zones, with the aim of improving their overall efficiency and reliability.